SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe2758e2dbd65e3f403b3c40642382f21978433a2c84d0d150c6b454ad4267f2' 
  AND token = 'T3gxFYphiH9NTC0K7rVLfiNAPuOaPS27cTmW9m9+MoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}